1. Sift flour and salt into a bowl; set aside.

2. Put butter and sugar in the bowl of an electric mixer fitted with the paddle attachment. Mix on medium speed until pale and fluffy. Mix in eggs and lemon juice. Reduce speed to low. Gradually mix in flour mixture. Divide dough in half; flatten each half into a disk. Wrap each in plastic. Refrigerate until firm, at least 1 hour or overnight.

3. Preheat oven to 350 degrees with racks in upper and lower thirds. Let one disk of dough stand at room temperature just until soft enough to roll, about 10 minutes. Place dough on a nonstick baking mat; place a piece of plastic wrap over dough. Roll out dough between baking mat and plastic wrap to 1/4 inch thick. Remove plastic wrap. Cut out cookies with a 5-inch butterfly- or dragonfly-shaped cookie cutter; cut out negative space in the wings using both sides of a small heart-shaped cookie cutter to create a mirror image (see Butterfly or Dragonfly templates). Use a drinking straw to create a hanging hole at top of cookie, if desired. Transfer baking mat to a baking sheet. Transfer baking sheet to freezer, freeze until very firm, about 15 minutes. Remove baking sheet from freezer; remove scraps and reposition cookies so that they are at least 1 inch apart. Roll out scraps, and repeat. Repeat with remaining disk of dough.

4. Transfer to oven and bake for 8 minutes. Let cool and sprinkle candy in a single layer in negative space of each cookie. Return to oven and bake until lightly golden, 8 to 10 minutes. Let cool on sheets on wire racks; carefully remove with a metal spatula.

5. Mix together some of the royal icing with food coloring until desired shade is reached for wings. Transfer to a small squirt bottle. Outline wings (see Butterfly or Dragonfly templates) with colored icing. Draw several zigzags across entire surface of the outlined area. If necessary, use a toothpick to spread evenly. Using tweezers, add candy decor to wing edges, if desired (see Butterfly or Dragonfly templates). Let dry.

6. Mix together some of the royal icing with food coloring until desired shade is reached for bodies. Transfer to a small squirt bottle. Outline body (see Butterfly or Dragonfly templates) with colored icing. Draw several zigzags across entire surface of the outlined area. If necessary, use a toothpick to spread evenly. Using tweezers, add dragees or candy eyes to create eyes (see Butterfly or Dragonfly templates). Let dry.